Eye Movements and Skills Performance Measures under Alcohol in a Driving Simulator

Abstract

Twenty-five male subjects in two groups (n's = 13 and 14) drove for 15 minutes in a simulator presenting a rural roadway scene. Subjects were required to maintain a constant heading angle, a constant speed, and to search for and respond appropriately to route signs. The two groups differed in training, the familiar group receiving training on the same route and signs in the experimental runs, the unfamiliar group being trained on different roadways and signs. After training, subjects attended three experimental runs under alcohol treatments producing mean blood alcohol concentrations of 0 (placebo), .085% and .125%. Results include large increases in dwell (fixation) and pursuit durations, indicating an increase in the time necessary to process information under alcohol. Alcohol also produced a large increase in very long duration fixations of over one second, which appeared to be non-productive “gazing.” The frequency of fixation decreased as the duration increased under alcohol. The effect of alcohol on the time to read the route signs was a joint function of the alcohol level, the amount of information in the sign and the familiarity with the sign. There was a greater increase in fixation duration for reading the route sign under alcohol for the unfamiliar group compared to the familiar group. Alcohol also increased speed and steering control errors.